Estoy tratando de escribir un código en p5.js y no puedo entender por qué el siguiente código arroja el error:

Error de referencia no detectado: RiLexicon no está definido

mySketch, línea 18: No se pueden leer las propiedades de undefined (leyendo 'isNoun')

Encendí la biblioteca RiTa.js pero no funciona. Espero que alguien pueda dar una idea.

 let poem = "STOPPING BY WOODS ON A SNOWY EVENING WHOSE woods these are I think I know. His house is in the village though; He will not see me stopping here To watch his woods fill up with snow. My little horse must think it queer To stop without a farmhouse near Between the woods and frozen lake The darkest evening of the year. He gives his harness bells a shake To ask if there is some mistake. The only other sound's the sweep Of easy wind and downy flake. The woods are lovely, dark and deep. But I have promises to keep, And miles to go before I sleep, And miles to go before I sleep." let words; let newPoem = ""; var lexicon = new RiLexicon(); function setup() { createCanvas(windowWidth, windowHeight); background(100); // tokenize the poem string to words words = RiTa.tokenize(poem); // replace all nouns and adjectives in the text with random nouns and adjectives. // loop through all the words for (i=0; i<words.length; i++){ let currentWord = words[i]; // when the word is a noun if (lexicon.isNoun(currentWord)){ // generate a new noun and use that as current word currentWord = lexicon.randomWord("nn"); } // when the word is an adj else if (lexicon.isAdjective(currentWord)){ // generate a new adj and use that as current word currentWord = lexicon.randomWord("jj"); } // add the word to the new poem newPoem += currentWord + " "; } print(newPoem); } function draw() { textSize(16); // display the new poem text(newPoem, width/20, height/4, 500, 800); }